Modern pacemakers monitor the activity of a heart and provide a stimulation pulse in the absence of normal heart activity. Such devices are relatively small, light-weight and implantable. In order to sense and stimulate the heart, however, such pacemakers must be used with a pacemaker lead—an electrical conductor that carries electrical signals between the heart and the pacemaker. Advantageously, the pacemaker lead can be inserted into the heart transvenously through a relatively simple and well-known surgical procedure. Disadvantageously, one end of the lead (designated herein as the “connecting end”) must be electrically and mechanically secured to the pacemaker in a way that provides for a long-term safe and secure, yet detachable, connection. Those skilled in the pacemaker art have long sought for a simple, yet reliable and safe, technique for making this detachable electrical and mechanical connection between the pacemaker device and the connecting end of the pacemaker lead.
In order to appreciate the advantages of the present invention, it will help first to have a basic understanding of the manner in which the mechanical and electrical connection functions are carried out in known pacemakers. The main components associated with the connection function of known pacemakers are shown in FIGS. 1 and 2. A pacemaker 10 electrically includes a battery 14 that powers electrical circuits 12. The pacemaker electrical circuits 12 and battery 14 are mechanically housed and hermetically sealed in a suitable housing 16. Typically, this housing 16 is shaped to include a flat side or platform 20 to which a suitable epoxy connector 22 can be bonded. At least one feedthrough terminal 18, in electrical contact with the electrical circuits 12, passes through the housing 16 and protrudes out from the platform 20. This feedthrough terminal 18 is electrically isolated from the housing 16. A platinum wire 24, or other suitable conductive element, connects the terminal 18 to a conductive connector block 26 that is fitted within the connector 22. A pacemaker lead 28, having a proximal electrode 30, connects to the pacemaker electrical circuits by inserting the proximal electrode 30 into a receiving channel 31 of the connector 22 until the electrode 30 is in contact with the connector block 24. A set screw 32 is then securely tightened using a torque wrench 34 to firmly hold the electrode 30 in both mechanical and electrical connection with the connector block 26. A septum (not shown) is typically placed over the set screw 32 in order to prevent body fluids from seeping through the set screw hole. Further, sealing ribs or ridges 36 on the connecting end of the pacemaker lead are designed to tightly engage the inside edges of the receiving channel 31 in order to prevent any body fluids from entering into the receiving channel 31 once the connecting end of the lead has been pushed into the connector 22.
Representative descriptions of many of the features and functions of prior art pacemaker connection systems may be found in U.S. Pat. No. 4,934,366 to Truex et al., U.S. Pat. Nos. 5,012,807 and 5,076,270 to Stutz, Jr., U.S. Pat. No. 5,336,246 to Dantanarayana, U.S. Pat. No. 5,545,188 to Bradswhaw et al.,U.S. Pat. No. 5,899,930 to Flynn et al., and U.S. Pat. No. 6,029,089 to Hawkins et al. as well as to EPO publications EP 448,651 to Truex et al., EP 484,483 to Stutz, Jr. and EP 732,124 to Yee et al. While that which is described in these prior art references varies greatly relative to, for example, different types of locking mechanisms for performing the mechanical connection function, or different types of arrangements for performing the electrical feedthrough function, including the use of bipolar or multiple connector leads, all such systems include the use of a pre-molded or cast connector 22 that is bonded to a sealed pacemaker housing 16 in which the electrical circuits are located.
Historically, the pacemaker connector top has included epoxy resin which was cast over connector assemblies (for example, set screw connector blocks, garter spring connector blocks, and the like) which were fixtured in a pre-arranged shape. The use of the conductor ribbon set offered a significant improvement in holding the connector blocks together in the desired pre-arranged shape during the casting process and produced an attractive finished product.
However, the tooling and assembly methods used, and the curing process itself, is time and labor intensive. There are issues with flashing, wire breaks, damaged can, bubbles, exposed components and epoxy in the bores. These problems add significant rework time. Furthermore, epoxy connector tops are still prone to body fluid absorption and corrosion.
What is needed is an improved connector top that is easy to manufacture, reliable, and cost effective.
It was in light of the foregoing that the present invention was conceived and has now been reduced to practice.